After baking indirect light, inside solid meshes is not dark in EEVEE
I found the answer myself.
In the properties panel there is a tab where you can find settings for the Irradiance Volume. 


Under Visibility Collection you can exclude a collection.  So In this case we add the cube to a collection (called test here) and when you bake indirect light now, everything will look the same from outside the cube, but inside the cube its now pretty dark.